Self-propelled tracked work vehicles, such as agricultural tractors and combines, are frequently provided with an undercarriage which supports a pair of idler wheels and, several roller wheels located between the idler wheels, over which wheels passes a track driven by a drive wheel. The roller wheels are intended to apply a downwardly directed force to the portion of the track between the idler wheels, which is in engagement with the surface supporting the vehicle.
Rubber tracked vehicles, and particularly those supported on four tracks, i.e. two spaced apart tracks on each side of the vehicle, have excellent ride characteristics in agricultural fields and reduce soil compaction, since the rubber track undercarriage spans most "holes" or surface irregularities in the fields, and distributes the downward force of the vehicle over a greater surface area. Tires typically fall into holes or other irregularities in the field causing a rough ride. Vehicle tire "power hop," a characteristic which also adversely affects field rides, is reduced by the use of tracks.
However, when rubber tracked vehicles are driven on hard surfaced roads, the ride is not as smooth as it would be with a tired vehicle. The rubber track provides little cushion between the track undercarriage and a hard surfaced road. Tires on an agricultural tractor provide the inherent characteristic of a large air bladder of approximately 18 inches in height, which cushions the vehicle from bumps and vibration as the tractor travels along a hard surface, such as a road. Thus, it would be desirable to place a suspension element between the roller wheel assemblies and the tractor which would smooth out the ride on a hard surfaces.
There have been many suspension elements developed for crawler type steel tracked vehicles in the past. However, what makes the rubber track undercarriages different, or unique, is the fact that the rubber track is extremely flexible and must be supported across the full face of the ground engaging portions of the belt to offer even ground weight distribution. Steel track crawler frames typically have narrow rollers which support a track which has inherent/built-in cross beams to distribute the weight across the width of the-track.
In order to provide a smooth ride on a hard surface, one presently available rubber tracked work vehicle is provided with pivot arms supported by an air bag located above the undercarriage assembly. However, when the drive wheel is located above the undercarriage, often referred to as a high drive type vehicle, it is difficult if not impossible to position the pivot arms and air bag above the undercarriage assembly. In a high drive type rubber track work vehicle, there is only a narrow space above the roller wheels, since the roller wheels are moved as close as possible to each other to more fully support the rubber track. Track tensioning mechanisms also need to be placed in the narrow space above the roller-wheels and below the drive wheel.
Accordingly, it would be advantageous to provide a support system for the rubber track of a rubber tracked vehicle, having a high drive wheel, which provides a smooth ride when travelling on a hard surface